The present invention relates generally to apparatus for controlling the flow of material. In one aspect the invention relates to an improved valve for controlling the flow of material therethrough. In another aspect the invention relates to apparatus suitable for use as a feeder for controlling the flow of material therethrough. A more specific aspect of the invention relates to the feeding of particulate catalyst to a catalytic reactor system.
The apparatus of the present invention is an improvement over the valve or feeder mechanisms disclosed in U.S. Pat. Nos. 3,219,208 and 3,139,996. Particulate catalyst, such as chromium oxide deposited on silica or silica-alumina, is relatively abrasive, and it has been found that feeder mechanisms for such catalyst are subject to undesirable wear between the rotary valve plug or rotor and the valve body in which the valve plug or rotor is carried. Such wear can cause both leakage of catalyst into the valve chamber through spaces worn between the valve plug or rotor and the valve body and increased operating torque required to rotate the valve plug or rotor relative to the valve body where the catalyst is in slurry form. Problems with plugging of the feeder can cause shutdown for cleaning. Plugging problems are worsened where the feeder conveys small slugs of catalyst, as in the case where a high productivity catalyst is used.